Orca--Take the Killer Whale for a Ride

What is this a11y thing (accessibility: 11 letters between the a and the y), and how might people access a complex graphical desktop they can't see?

Orca is a free, open-source, extensible screen reader that provides
access to the graphical desktop via user-customizable combinations of
speech, Braille and/or magnification. In this article, I briefly
discuss how to set up and use Orca on the GNOME desktop. This article's
intended audience includes not only users with visual
impairments, but also developers interested in improving the
accessibility of their applications.

Figure 1. Orca Swimming in the AT-SPI Sea

Orca works with applications and toolkits that support the assistive
technology service provider interface (AT-SPI), which is the primary
assistive technology infrastructure for Linux and the Solaris
operating environment. Applications and toolkits supporting the AT-SPI
include the GNOME GTK+ toolkit, the Java platform's Swing toolkit,
OpenOffice.org and Mozilla (KDE/Qt support for AT-SPI remains under
investigation). As a result, Orca can provide access to applications,
such as Firefox 3, Thunderbird 3, OpenOffice.org, most GNOME applications
and a wide variety of multimedia applications.

Via the AT-SPI, Orca connects to applications and communicates with
their graphical components, such as push buttons, text areas, menus
and so forth. As you interact with an application, the AT-SPI notifies Orca.
In response, Orca presents appropriate information to the user via
speech synthesis (the machine talks to you), refreshable Braille (an
external hardware device) and/or magnification (an enlarged view of
the graphical display). Orca also provides mechanisms for you to
explore the entire contents of windows presented by the application.

Orca is known as a scriptable screen reader, meaning it can provide
customized behavior based on the application with which it is
working. With Orca, custom scripts written in the Python programming
language can be used to provide more compelling access to the unique
interaction models of applications. For example, Orca provides a
script for the Pidgin instant-messaging application to give you
additional features, such as quickly reviewing the last few messages
that have arrived.

Note to application developers: Orca provides a default script that
gives access to the majority of applications. As a result, a custom
script is not required for each application. The Orca team encourages
you to test your applications using Orca, however, and to create a
custom Orca script if it is needed. The Orca team is happy to help
you!

Prerequisites

In order to use Orca, you need a desktop environment that supports the
AT-SPI, such as GNOME. Fortunately, GNOME is widely available on many
operating system distributions, including Ubuntu, Fedora, Debian,
OpenSUSE, Solaris Express and so on. Although Orca works on GNOME 2.18 and
better, GNOME 2.20 or better are the versions in which Orca works
best. Because Orca also is under constant development, the brave are
encouraged to use the latest sources. See the “Downloading and
Installing Orca” page of the Orca Wiki for more information on
working with Orca sources.

To use speech, Orca currently uses gnome-speech to communicate with
speech synthesis engines on the machine. On Linux systems, there are a
variety of free, open-source engines available, including eSpeak
and Festival. Most operating system distributions typically provide
gnome-speech and at least one speech synthesis engine. To determine whether
Orca can use speech on your machine, run the test-speech
application provided by gnome-speech. If you can get your machine to
speak using test-speech, it should work with Orca. See the
“Speech”
page on the Orca Wiki for more information on setting up speech on
your system.

A typical Braille user will have purchased an external hardware device
called a refreshable Braille display. These devices provide a number
of Braille cells—typically 40 or so—where each cell comprises
eight
dots that a software application can pop up or down to create a
Braille character. Orca uses a separate software application, called
BrlTTY, to communicate with refreshable Braille displays. Like
gnome-speech, many operating system distributions install BrlTTY by
default. The configuration of BrlTTY is outside the scope of this
article, but more information can be found at the BrlTTY site and on
the “Braille” page of the Orca Wiki.

Figure 2. Refreshable Braille Display

For application developers without a refreshable Braille display, Orca
provides a graphical Braille monitor to present what would be sent to
the Braille display. The Braille monitor is independent of BrlTTY and
also is useful for demonstrating Orca to other people.

Figure 3. Orca's Braille Monitor

Orca currently uses gnome-mag for magnification. As with gnome-speech
and BrlTTY, the operating system distribution includes gnome-mag by
default. You can tell whether your machine has gnome-mag installed if the
gnome-mag magnifier application is on your machine.

Comments

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Some applications work better than others, however, and the Orca community continually works to provide compelling access to more applications. Orca is already provided by default on a number of operating system distributions, including Open Solaris, Fedora, and Ubuntu.

I've been using Orca in my 8.9" netbook and this really helps me a lot, despite my hearing impairment. That braille display in the image looks kind of nice, though, and it can go hand-on-hand with my netbook. However, if only I could afford to get a Braille display. I've been keeping an eye on prototype affordable braille displays out there in the Internet (Google "prototype affordable braille display" with quotes). I don't like to loan an expensive braille display, even if I don't want to make a very major purchase if I earn about $4,000 a month...

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